PKI-166 hydrochloride is primarily used in research settings as a potent and selective inhibitor of the epidermal growth factor receptor (EGFR) tyrosine kinase. Its application is significant in the study of cancer biology, particularly in understanding the role of EGFR in tumor growth and progression. Researchers utilize this compound to investigate the mechanisms of EGFR signaling pathways and to evaluate its potential as a therapeutic target in various cancers, including lung, breast, and colorectal cancers. Additionally, PKI-166 hydrochloride is employed in preclinical studies to assess the efficacy and safety of EGFR inhibitors in animal models, providing valuable insights for the development of targeted cancer therapies. Its ability to inhibit EGFR activation makes it a crucial tool in the exploration of novel treatment strategies for EGFR-driven malignancies.